近邻元素掺杂YMn0.5Cr0.5O3钙钛矿结构氧化物中的亚铁磁性和B位有序研究

项目名称： 近邻元素掺杂YMn0.5Cr0.5O3钙钛矿结构氧化物中的亚铁磁性和B位有序研究

项目编号： No.11474262

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 朱弘

作者单位： 中国科学技术大学

项目金额： 91万元

中文摘要： 钙钛矿结构氧化物中B位阳离子有序是一种新的物性调控手段，它通常发生在两种阳离子半径和价态差别较大的体系中。本项目以近邻元素掺杂的YMn0.5Cr0.5O3为对象，研究其亚铁磁性背后隐含的B位阳离子有序现象，以及磁性离子间的交换作用形式。将通过元素替位方法，分别增大A位离子半径和减少B位杨-泰勒效应离子的含量，观察亚铁磁基态的变化，澄清八面体倾斜和杨-泰勒畸变对B位阳离子有序的影响。制备单晶样品和外延薄膜，采用电子衍射、高分辨电镜等多种手段表征B位有序的微结构，并且研究样品的各向异性、磁电耦合/多铁性以及薄膜的应变效应。利用第一性原理计算方法进行理论计算研究，对比分析计算获得的结构、磁性基态与实验结果的异同，为实验研究提供参考指导。研究结果有助于深化对钙钛矿结构氧化物中复杂现象的认识，特别是晶格/轨道自由度所起的作用，并且对新型B位有序材料的探索，将为功能氧化物的设计开发提供更多的科学依据。

中文关键词： 磁有序；磁电耦合；多铁性；磁性薄膜；第一性原理计算

英文摘要： B-site cation ordering, which usually occurs when the differences of radius and valance state between the two cations are large, has been used with much success to expand the perovskite family and engineer new materials. Focusing on the neighboring element doped YMn0.5Cr0.5O3 oxide, in this project we will study the B-site cation ordering phenomenon implied by the ferrimagnetism of the system, as well as the details of the exchange interactions between magnetic cations. Increasing the average radius of A-site cation and decreasing the content of Jahn-Teller active cation at B-site respectively by using the element substitution method, we will investigate the evolution of ferrimagnetic ground state to clarify the influences of octahedral tilting and Jahn-Teller distortion on the B-site cation ordering. By growing single crystals and high-quality epitaxial films, we will characterize the B-site ordered microstructure in detail by using electron diffraction, high-resolution electron microscopy and other advanced techniques. We will also study the anisotropic properties, magnetoelectric coupling/multiferroics and strain effects for the epitaxial thin films. Employing the first-principles calculations on structure and magnetism, we will compare the calculated results with the experimental results to provide the theoretical guidance. The research results will be helpful to understand the complex phenomena, especially the role of lattice/orbital degree of freedom, in perovskite oxides more thoroughly. And the exploration of novel B-site cation ordered perovskite oxides will provide more solid scientific bases for the R&D of functional oxides.

英文关键词： magnetic order;magnetoelectric coupling;multiferroics;magnetic film;first-principles calculation